3.1、Dao 代理实现 CURD

（**1） 去掉 Dao **接口实现类

（**2） getMapper **获取代理对象
只需调用 SqlSession的 getMapper()``方法，即可获取指定接口的实现类对象。该方法的参数为指定 Dao接口类的 class 值。

SqlSession session = factory.openSession();
StudentDao dao = session.getMapper(StudentDao.class);

使用工具类：

StudentDao studentDao = MyBatisUtil.getSqlSession().getMapper(StudentDao.class);

（**3） 使用 Dao 代理对象方法执行 sql **语句

package com.wzy.dao;
import com.wzy.pojo.Student;
import com.wzy.utils.MyBatilsUtils;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;
import java.io.IOException;
import java.io.InputStream;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
public class StudentDaoTest2 {
    @Test
    public void selectStudents() {
        //1.获取代理对象
        StudentDao studentDao = MyBatilsUtils.getSqlSession().getMapper(StudentDao.class);
        //2.调用查询方法
        List<Student> studentList = studentDao.selectStudents();
        //3.输出结果
        studentList.forEach(student -> System.out.println(student));
    }
    @Test
    public void insertStudent() throws ParseException {
        SqlSession sqlSession = null;
        try {
            //1.获取代理对象
            sqlSession = MyBatilsUtils.getSqlSession();
            StudentDao studentDao = sqlSession.getMapper(StudentDao.class);
            //2.调用方法执行sql语句
            int result = studentDao.insertStudent(new Student(null, "莉莉", "女", 15,
                    new SimpleDateFormat("yyyy-MM-dd").parse("2006-5-26"), null));
            //3.没有异常提交数据
            sqlSession.commit();
            System.out.println("成功插入了" + result + "条数据!");
        } catch (ParseException e) {
            e.printStackTrace();
            sqlSession.rollback();
        } finally {
            if (sqlSession != null) {
                sqlSession.close();
            }
        }
    }
    @Test
    public void upDateStudent() {
        SqlSession sqlSession = null;
        Date parse = null;
        try {
            sqlSession = MyBatilsUtils.getSqlSession();
            StudentDao studentDao = sqlSession.getMapper(StudentDao.class);
            parse = new SimpleDateFormat("yyyy-MM-dd").parse("1996-8-20");
            int result = studentDao.updateStudent(new Student(13, "花花", "女", 25, parse, null));
            sqlSession.commit();
            System.out.println("成功修改了" + result + "条数据!");
        } catch (ParseException e) {
            e.printStackTrace();
            sqlSession.rollback();
        } finally {
            if (sqlSession != null) {
                sqlSession.close();
            }
        }
    }
    @Test
    public void deleteStudent() {
        SqlSession sqlSession = null;
        try {
            String config = "MyBatis.xml";
            InputStream resourceAsStream  = Resources.getResourceAsStream(config);
            SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(resourceAsStream);
            sqlSession = factory.openSession();
            StudentDao studentDao = sqlSession.getMapper(StudentDao.class);
            int result = studentDao.deleteStudent(13);
            sqlSession.commit();
            System.out.println("成功删除了" + result + "条记录!");
        } catch (IOException e) {
            e.printStackTrace();
            sqlSession.rollback();
        } finally {
            if (sqlSession != null) {
                sqlSession.close();
            }
        }
    }
}